Microsatellite instability in endometrial cancer: Relation to histologicalsubtypes

Fifty-one endometrial cancers were analyzed with regard to whether or how m icrosatellite instability (MI) was associated with the development of diffe rent types of endometrial malignant neoplasms. We investigated 6 loci previ ously reported as informative for colorectal cancer and a group of 8 loci l ocated on 6q, Replication error (RER+) phenotype was detected in 10 of 51 ( 19.6%) endometrial cancers (ECs), all but one of which showed endometrioid differentiation. On the contrary, the RER+ phenotype was not detected in se rous carcinomas and malignant mixed Mullerian tumors, MI was present in bot h early and advanced stage ECs, No correlation was found between age, grade , stage, familial pattern, mitotic index, and the RER+ phenotype of ECs, On ly 1 of 8 endometrial carcinomas showing MI was associated with mutant p53 expression, while the majority of RER+ tumors were positive for estrogen an d progesterone receptors. Our findings suggest that MI plays an early role in endometrial tumorigenesis and is significantly correlated with adenocarc inomas showing endometrioid features (EAs), The frequent involvement of the telomeric region of chromosome 6 in the MI of EA is an indication that thi s region may be crucial in the process of EA tumorigenesis. (C) 1999 Academ ic Press.